Refrigerating device and refrigerator

ABSTRACT

There are provided a refrigerating device capable of efficiently performing a refrigerant recovering operation even in a case where there are disposed a plurality of heat absorbing units functioning in different temperature zones, and a refrigerator including this refrigerating device. A refrigerating device  30  includes a compressor  1 , a radiator  2 , an expansion valve  3 , a gas-liquid separator  4 , a first heat absorbing unit  10  through which a liquid refrigerant from this gas-liquid separator  4  flows, and a second heat absorbing unit  11 , and the refrigerating device performs a refrigerant recovering operation of stopping circulation of the refrigerant into the second heat absorbing unit  11 , operating the compressor  1 , recovering the refrigerant stored in a heat sink  58 , and sending the refrigerant to the gas-liquid separator  4  to store the refrigerant in a state in which circulation of the refrigerant into the first heat absorbing unit  10  is stopped after ending a freezing operation.

BACKGROUND OF THE INVENTION

The present invention relates to a refrigerating device provided with aplurality of heat absorbing means which function in differenttemperature zones, and a refrigerator provided with this refrigeratingdevice.

As a refrigerating device provided with a plurality of heat absorbingmeans which function in different temperature zones, there is known, forexample, a refrigerator having: heat absorbing means for refrigerating;and heat absorbing means for freezing which functions at a temperaturelower than that of the heat absorbing means for refrigerating. Therespective heat absorbing means are operated to perform a freezingoperation and a refrigerating operation. However, in such refrigerator,a refrigerant pools in a heat sink of the heat absorbing means forfreezing, for example, during the freezing operation. Thereafter, in acase where the refrigerating operation is performed, there is a problemthat an amount of the refrigerant in a refrigeration cycle becomesunstable.

In Japanese Patent Application Laid-Open No. 2001-221556, it isdisclosed that a refrigerant recovering operation is performed as amethod of precisely controlling an amount of a refrigerant to becirculated in the refrigeration cycle and reducing a refrigerantbehavior delay in a refrigerator provided with the above-described heatabsorbing means for refrigerating and heat absorbing means for freezing.In the operation, a compressor is operated while interrupting inflow ofthe refrigerant into the heat absorbing means for freezing after thefreezing operation ends. Moreover, a fan for a radiator is operated, therefrigerant from the heat absorbing means for freezing is recovered, andthe recovered refrigerant is sent to the radiator to condense.

However, the above-described conventional refrigerating device has aproblem that during the refrigerant recovering operation, the fan forthe radiator needs to be operated in order to allow the refrigerant sentto the radiator to condense, and power consumption and refrigeratingdevice operation noise increase in some case. There is also a problemthat the refrigerant cannot condense in the radiator in therefrigerating device having a supercritical pressure in ahigh-pressure-side circuit.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide arefrigerating device capable of efficiently performing a refrigerantrecovering operation even in a case where the device includes aplurality of heat absorbing means functioning in different temperaturezones, and a refrigerator including this refrigerating device.

In a first aspect of the present invention, there is provided arefrigerating device provided with a refrigeration cycle including: acompressor; a radiator connected to a discharge side of the compressor;first pressure reducing means connected to an outlet side of theradiator; a gas-liquid separator connected to an outlet side of thefirst pressure reducing means; first heat absorbing means through whicha liquid refrigerant from the gas-liquid separator flows and whichincludes second pressure reducing means and a first heat sink; andsecond heat absorbing means disposed in parallel with the first heatabsorbing means and including third pressure reducing means and a secondheat sink, refrigerant pipes of the first and second heat absorbingmeans on the outlet side being combined and connected to a suction sideof the compressor, the second heat absorbing means functioning in atemperature zone lower than that of the first heat absorbing means, afirst cooling operation to operate the first heat absorbing means and asecond cooling operation to operate the second heat absorbing meansbeing switchable to each other, the refrigerating device comprising:control means for performing a refrigerant recovering operation to stopcirculation of the refrigerant into the second heat absorbing means,operate the compressor, recover the refrigerant stored in the secondheat sink, and store the refrigerant in the gas-liquid separator in astate in which circulation of the refrigerant into the first heatabsorbing means is stopped after the second cooling operation iscompleted.

In the invention of a second aspect, the refrigerating device of thefirst aspect further comprises: blowing means for sending air to thesecond heat sink, and the blowing means is operated during therefrigerant recovering operation.

In the invention of a third aspect, in the refrigerating device of thefirst or second aspect, the compressor has an intermediate pressuresection, and the refrigerating device further comprises: a refrigerantpipe capable of introducing a gas refrigerant separated by thegas-liquid separator into the intermediate pressure section.

In the invention of a fourth aspect, in the refrigerating device of anyone of the first to third aspects, a high-pressure side of therefrigeration cycle is operated with a supercritical pressure.

In the invention of a fifth aspect, in the refrigerating device of anyone of the first to fourth aspects, the refrigerant recovered from thesecond heat sink is stored in the gas-liquid separator in a case wherethe high-pressure side of the refrigeration cycle is operated with thesupercritical pressure, and the refrigerant recovered from the secondheat sink is stored in the gas-liquid separator and/or the radiator in acase where the high-pressure side of the refrigeration cycle is notoperated with the supercritical pressure.

In the invention of a sixth aspect, in the refrigerating device of thefifth aspect, the blowing means for sending air to the radiator isdisposed close to the radiator, and the blowing means is operated at atime when the refrigerant recovered from the second heat sink is storedin the radiator.

In a seventh aspect, there is provided a refrigerating device providedwith a refrigeration cycle including: a compressor; a radiator connectedto a discharge side of the compressor; first pressure reducing meansconnected to an outlet side of the radiator; a gas-liquid separatorconnected to an outlet side of the first pressure reducing means; firstheat absorbing means through which a liquid refrigerant from thegas-liquid separator flows and which includes second pressure reducingmeans and a first heat sink; and second heat absorbing means disposed inparallel with the first heat absorbing means and including thirdpressure reducing means and a second heat sink, refrigerant pipes of thefirst and second heat absorbing means on the outlet side being combinedand connected to a suction side of the compressor, wherein the secondheat absorbing means functions in a temperature zone lower than that ofthe first heat absorbing means, a first cooling operation to operate thefirst heat absorbing means and a second cooling operation to operate thesecond heat absorbing means are switchable to each other, therefrigerating device permitting circulation of the refrigerant into thefirst heat absorbing means, stopping circulation of the refrigerant intothe second heat absorbing means, and operating the compressor at afrequency higher than that of the first or second cooling operationbefore starting the first cooling operation.

In an eighth aspect, there is provided a refrigerating device providedwith a refrigeration cycle including: a compressor; a radiator connectedto a discharge side of the compressor; first pressure reducing meansconnected to an outlet side of the radiator; a gas-liquid separatorconnected to an outlet side of the first pressure reducing means; firstheat absorbing means through which a liquid refrigerant from thegas-liquid separator flows and which includes second pressure reducingmeans and a first heat sink; and second heat absorbing means disposed inparallel with the first heat absorbing means and including thirdpressure reducing means and a second heat sink, refrigerant pipes of thefirst and second heat absorbing means on the outlet side being combinedand connected to a suction side of the compressor, wherein the secondheat absorbing means functions in a temperature zone lower than that ofthe first heat absorbing means, a first cooling operation to operate thefirst heat absorbing means and a second cooling operation to operate thesecond heat absorbing means are switchable to each other, therefrigerating device operating a refrigerant recovering operation ofpermitting circulation of the refrigerant into the first heat absorbingmeans, stopping circulation of the refrigerant into the second heatabsorbing means, operating the compressor at a frequency higher thanthat of the first or second cooling operation, recovering therefrigerant stored in the second heat sink, and sending the refrigerantto the gas-liquid separator to store the refrigerant before starting thefirst cooling operation.

In the invention of a ninth aspect, the refrigerating device of theseventh or eighth aspect further comprises: blowing means for sendingair to the second heat sink, and the blowing means is operated in a casewhere the compressor is operated at the high frequency.

In the invention of a tenth aspect, in the refrigerating device of anyone of the first to ninth aspects, carbon dioxide is used as therefrigerant.

In an eleventh aspect of the present invention, a refrigeratorcomprises: a refrigerating device in any one of the first to tenthaspects.

In a twelfth aspect of the present invention, the refrigerator of theeleventh aspect further comprises: a refrigerating chamber; and afreezing chamber operated at a temperature lower than that of therefrigerating chamber, the refrigerating chamber is cooled by the firstheat absorbing means, and the freezing chamber is cooled by the secondheat absorbing means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a refrigerant circuit diagram showing a refrigerating devicein one embodiment of the present invention;

FIG. 2 is an enthalpy and pressure graph of a refrigeration cycle of therefrigerating device in the embodiment of the present invention;

FIG. 3 is an enthalpy and pressure graph of a supercriticalrefrigeration cycle of the refrigerating device in the embodiment of thepresent invention;

FIG. 4 is a timing chart showing a first control method in therefrigerating device of the embodiment of the present invention;

FIG. 5 is a timing chart showing a second control method in therefrigerating device of the embodiment of the present invention;

FIG. 6 is a schematic constitution diagram showing an example in whichthe refrigerating device of the embodiment of the present invention isapplied to a refrigerator;

FIG. 7 is a refrigerant circuit diagram showing a refrigerating devicein another embodiment of the present invention; and

FIG. 8 is a refrigerant circuit diagram showing a refrigerating devicein still another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will be described hereinafter indetail with reference to the drawings.

Embodiment 1

One embodiment of the present invention will be described in detail withreference to the drawings. FIG. 1 shows a refrigerant circuit diagram ofa refrigerating device in one embodiment of the present invention. Arefrigerating device 30 includes: a compressor 1; a radiator 2 connectedto a discharge side of the compressor 1; a fan 2F which is disposedclose to this radiator 2 and which cools a refrigerant in the radiator2; an expansion valve 3 as pressure reducing means connected to anoutlet side of the radiator 2; a gas-liquid separator 4 connected to arefrigerant pipe 4A on an outlet side of this expansion valve 3; arefrigerant pipe 4B in which a liquid refrigerant separated from thisgas-liquid separator 4 circulates; first heat absorbing means 10connected to one side from a branch point 9A from which this refrigerantpipe 4B is branched; and second heat absorbing means 11 connected to theother side from the branch point, disposed in parallel with the firstheat absorbing means 10, and functioning in a temperature zone differentfrom that of the first heat absorbing means 10. A refrigerant pipe 4C inwhich a gas refrigerant separated from the gas-liquid separator 4 flowsis connected to an intermediate pressure section of the compressor 1,refrigerant pipes from the heat absorbing means 10, 11 are combined witheach other in a confluent point 9B, and the subsequent refrigerant pipeis connected to a suction port of the compressor 1, thereby forming arefrigeration cycle

Furthermore, the refrigerating device 30 includes: a stop valve 7disposed between the gas-liquid separator 4 and the intermediatepressure section of the compressor 1; a stop valve 53 disposed betweenthe confluent point 9B and the suction port of the compressor 1; and acontrol device 26.

The first heat absorbing means 10 includes: an expansion valve 65 aspressure reducing means; and a heat sink 57 connected in series to thisexpansion valve 65. The second heat absorbing means 11 includes anexpansion valve 66 as pressure reducing means; and a heat sink 58connected in series to this expansion valve 66. A stop valve 52 isdisposed between the heat sink 58 and the confluent point 9B.

Here, the expansion valves 3, 65, and 66 are constituted so that asqueezing degree is variable. In the expansion valves 65 and 66, thesqueezing degree of each valve is changed to lower a pressure of therefrigerant down to a predetermined pressure before the refrigerantreaches the heat sinks 57, 58, so that an evaporation temperature of therefrigerant can be controlled in the heat sinks 57, 58. The expansionvalves 65, 66 have a function of refrigerant channel switching means.When one of the expansion valves 65 and 66 is fully closed, the means ofswitched to the first heat absorbing means 10 or the second heatabsorbing means 11, and the refrigerant can be selectively circulated toone of the means. When the squeezing degree of the expansion valve 3 ischanged, the pressure of the refrigerant is lowered to the predeterminedpressure before the refrigerant reaches the gas-liquid separator 4, anda gas refrigerant is generated. When the refrigerant is fed into thegas-liquid separator 4 in this state, a separation efficiency in thegas-liquid separator 4 can be changed.

The compressor 1 is a two-stage compressor, a sealed container containsa first-stage compressing section 1A and a second-stage compressingsection 1B, and an intermediate cooler 1C is disposed in the refrigerantpipe extending out of the sealed container in which the first-stagecompressing section 1A is connected to the second-stage compressingsection 1B. The refrigerant pipe 4C is connected to the compressor sothat the gas refrigerant separated from the gas-liquid separator 4 canbe introduced into the intermediate pressure section of the compressor1, that is, between the intermediate cooler 1C and the second-stagecompressing section 1B as described above. It is to be noted that thegas refrigerant is introduced into the intermediate pressure section ofthe compressor 1 as shown by a broken-line arrow owing to a differencepressure in the refrigerant pipe 4C. The compressor 1 is not limited tothe two-stage compressor. When the compressor is, for example, aone-stage compressor, the refrigerant pipe 4C may be returned to anintermediate pressure section of the one-stage compressor.Alternatively, a plurality of compressors may be connected.

Furthermore, in the refrigerating device 30 of the present embodiment,fans 57F, 58F are disposed close to the heat sinks 57, 58, respectively.Moreover, cold air generated by the heat sink 57 is sent to arefrigerating chamber 21 via a duct 57A by the fan 57F, cold airgenerated by the heat sink 58 is sent to a freezing chamber 22 via aduct 58A by the fan 58F, and the chambers 21, 22 are cooled at apredetermined temperature, respectively. The chambers 21, 22 areprovided with temperature sensors 21T, 22T.

The control device 26 is control means for controlling an operationfrequency or an on/off state of the compressor 1, open degrees of theexpansion valves 3, 65, and 66, on/off states of the fans 2F, 57F, and58F and the like based on information of the temperature sensors 21T,22T and the like. The device is constituted of, for example, ageneral-purpose microcomputer.

Moreover, in the refrigerating device 30 of the present embodiment, acarbon dioxide refrigerant (CO₂) which is a natural refrigerant isintroduced as a refrigerant having a small load on environment inconsideration of combustibility, toxicity and the like. As an oil as alubricant of the compressor 1, there is used, for example, mineral oil,alkyl benzene oil, ether oil, polyalkylene glycol (PAG), polyol ester(POE) or the like.

There will be described an operation of the refrigerating device 30constituted as described above in the present embodiment with referenceto FIGS. 1, 2, and 3.

FIG. 2 is an enthalpy and pressure (ph) graph of the refrigeration cyclein the embodiment, and FIG. 3 is an enthalpy and pressure (ph) graph ina case where there is a supercritical pressure in a high-pressure-sidecircuit in the refrigeration cycle.

First, a freezing operation (e.g., around −26° C.) will be describedusing a cycle shown by a solid line in FIG. 2. It is to be noted thatthis freezing operation refers to a case where the expansion valve 65 isclosed by the control device 26 to circulate the refrigerant on a secondheat absorbing means 11 side.

When the compressor 1 is operated in the present embodiment, therefrigerant discharged from the compressor 1 radiates heat, and iscooled in the radiator 2. That is, first the refrigerant is circulatedin order of: (1) suction into the first-stage compressing section 1A;and (2) discharge from the first-stage compressing section 1A, andcooled in the intermediate cooler 1C. Thereafter, the refrigerant iscirculated in order of: (3) suction into the second-stage compressingsection 1B; and (4) discharge from the second-stage compressing section1B to an inlet of the radiator 2. Moreover, the refrigerant reaches (5)an outlet of the radiator 2 and an inlet of the expansion valve 3, and(6) outlet of the expansion valve 3, and in this state, the refrigerantconstitutes a two-phase mixture of a gas and a liquid.

Here, a ratio between the gas and the liquid corresponds to a ratiobetween a length (gas) of a line segment of (6) to (7) and a length(liquid) of a line segment from (6) to (21). This refrigerant enters thegas-liquid separator 4 in the form of the two-phase mixture. Moreover,the gas refrigerant separated here is introduced into the intermediatepressure section of the compressor 1, that is, between the intermediatecooler 1C and the second-stage compressing section 1B by the refrigerantpipe 4C. In this case, (21) denotes an outlet of the gas-liquidseparator 4. The gas refrigerant discharged from the separator reaches(3) the suction of the second-stage compressing section 1B, and iscompressed by the second-stage compressing section 1B. On the otherhand, the liquid refrigerant separated by the gas-liquid separator 4reaches the expansion valve 66 via the confluent point 9A. In this case,(7) denotes the outlet of the gas-liquid separator 4 and the inlet ofthe expansion valve 66, (8) denotes an outlet of the expansion valve 66and an inlet of the heat sink 58, and (22) denotes an outlet of the heatsink 58. After entering the heat sink 58, the liquid refrigerantevaporates, absorbs heat from its periphery, and returns to (1) thesuction into the first-stage compressing section 1A.

On the other hand, during the refrigerating operation (e.g., around −5°C.), a cycle is formed as shown by broken lines in FIGS. 2 and 3. It isto be noted that the refrigerating operation is a case where theexpansion valve 66 is closed by the control device 26 to circulate therefrigerant on a first heat absorbing means 10 side.

Also in this case, when the compressor 1 is operated, the refrigerantdischarged from the compressor 1 radiates heat, and is cooled in theradiator 2. That is, the refrigerant is circulated in order of: (9)suction into the first-stage compressing section 1A; and (10) dischargefrom the first-stage compressing section 1A, and cooled in theintermediate cooler 1C. Thereafter, the refrigerant is circulated inorder of: (11) suction into the second-stage compressing section 1B; and(12) discharge from the second-stage compressing section 1B to the inletof the radiator 2. Moreover, the refrigerant reaches (5) the outlet ofthe radiator 2 and the inlet of the expansion valve 3, and (16) theoutlet of the expansion valve 3, and in this state, the refrigerantconstitutes a two-phase mixture of a gas and a liquid.

Here, a ratio between the gas and the liquid corresponds to a ratiobetween a length (gas) of a line segment of (16) to (14) and a length(liquid) of a line segment from (16) to (17). This refrigerant entersthe gas-liquid separator 4 in the form of the two-phase mixture.Moreover, the gas refrigerant separated here is introduced into theintermediate pressure section of the compressor 1, that is, between theintermediate cooler 1C and the second-stage compressing section 1B bythe refrigerant pipe 4C. In this case, (17) denotes an outlet of thegas-liquid separator 4. The gas refrigerant discharged from theseparator reaches (11) the suction of the second-stage compressingsection 1B, and is compressed by the second-stage compressing section1B. On the other hand, the liquid refrigerant separated by thegas-liquid separator 4 reaches the expansion valve 66 via the confluentpoint 9A. In this case, (14) denotes the outlet of the gas-liquidseparator 4 and the inlet of the expansion valve 65, (15) denotes anoutlet of the expansion valve 65 and an inlet of the heat sink 57, and(24) denotes an outlet of the heat sink 57. After entering the heat sink57, the liquid refrigerant evaporates, absorbs heat from its periphery,and returns to (9) the suction into the first-stage compressing section1A.

During both the freezing operation and the refrigerating operation, therefrigerant circulates to change its state as described above, and therefrigeration cycle is formed. The control device 26 operates the fan58F during the freezing operation, and operates the fan 57F during therefrigerating operation to thereby cool the chambers 22, 21,respectively.

It is to be noted that since carbon dioxide is used as the refrigerantin the present embodiment, the high-pressure-side circuit is operatedunder a supercritical pressure as shown in the enthalpy and pressure(ph) graph of FIG. 3 on the conditions that, for example, an outside airtemperature is about 30° C. or more in summer, or a cooling loadincreases. Even in this case, it is possible to perform the freezingoperation and the refrigerating operation in the same manner as in therefrigeration cycle shown in FIG. 2 as described above.

Moreover, in the freezing and refrigerating operations, even if the gasrefrigerant separated by the gas-liquid separator 4 is circulated in theheat absorbing means 10, 11, respectively, the refrigerant cannot beused in cooling. When the refrigerant is returned to the suction of thefirst-stage compressing section 1A, a refrigeration cycle efficiency islowered.

To solve the problem, in the present embodiment, since the gasrefrigerant separated by the gas-liquid separator 4 is introduced intothe intermediate pressure section of the compressor 1, that is, betweenthe intermediate cooler 1C and the second-stage compressing section 1B,the refrigeration cycle efficiency can be improved. Especially in thepresent embodiment, since carbon dioxide is used as the refrigerant, agas content increases in the ratio of the gas and the liquid separatedby the gas-liquid separator 4 as compared with a Freon-basedrefrigerant, a hydrocarbon-based refrigerant or the like. When a largegas content is introduced into the intermediate pressure section of thecompressor 1, the refrigeration cycle efficiency can further beimproved.

Furthermore, in the present embodiment, the heat sinks 57, 58 areselectively used based on a use temperature zone as described above. Inconsequence, in the freezing operation and the refrigerating operationhaving different temperature zones, the heat sink suitable for thetemperature is usable, and there can be expected improvement of anoperation efficiency of each operation.

It is to be noted that the refrigerating device 30 of the presentembodiment includes the heat sinks 57, 58 which function in differenttemperature zones as described above. However, the refrigerant sometimespools in the heat sink 58 during, for example, the freezing operationperformed at a temperature lower than that of the refrigeratingoperation. In a low-pressure-side circuit of the present embodiment,that is, from the expansion valves 65 and 66 to the suction port of thefirst-stage compressing section 1A via the confluent point 9B, as shownalso in FIGS. 2 and 3, the pressure in the low-pressure-side circuitbecomes higher during the refrigerating operation rather than during thefreezing operation. On the outlet side of the heat sink 58, there isdisposed the stop valve 52 for preventing a high-temperature refrigerantfrom being discharged into the heat sink 58 during the refrigeratingoperation.

Therefore, the refrigerant stored in the heat sink 58 during thefreezing operation as described above does not circulate in therefrigeration cycle during the subsequent refrigerating operation, andan amount of the refrigerant in the refrigeration cycle is unstableduring the refrigerating operation.

Next, there will be described a refrigerant recovering operation in therefrigerating device 30 of the present embodiment with reference toFIGS. 4 and 5. FIG. 4 is a timing chart showing a first control methodin the refrigerating device 30, and FIG. 5 is a timing chart showing asecond control method in the refrigerating device 30.

First Control Method

There will be described a first control method in the present embodimentwith reference to FIG. 4. In this first control method, a refrigerantrecovering operation is executed at a time when the freezing operationis stopped. It is to be noted that in the present embodiment, there willbe first described a case where the freezing operation is performed, butthe freezing operation does not have to be performed first in thepresent invention.

First, the freezing operation is performed. In the present freezingoperation, the control device 26 closes the expansion valve 65, andopens the expansion valve 66. The device turns off the fan 57F, andturns on the fan 58F. Accordingly, the freezing operation is performedas described above.

Next, the refrigerant recovering operation is performed. Thisrefrigerant recovering operation is an operation to recover therefrigerant stored in the heat sink 58 during the freezing operation.That is, in the freezing operation, when a temperature detected by thetemperature sensor 22T in the freezing chamber 22 reaches apredetermined temperature (e.g., −26° C.), the control device 26executes the refrigerant recovering operation.

In the present refrigerant recovering operation, the control device 26closes the expansion valve 66 in addition to the expansion valve 65. Thecompressor 1 and the fan 58F are turned on. Accordingly, evaporation ofthe refrigerant stored in the heat sink 58 is promoted by the fan 58F,and the stored refrigerant is sucked and recovered by the compressor 1.Moreover, the recovered refrigerant is discharged by the compressor 1.The refrigerant discharged by the compressor 1 in this manner flowsthrough the radiator 2. After the pressure of the refrigerant is reducedby the expansion valve 3, the refrigerant is sent to the gas-liquidseparator 4, and separated into the gas and the liquid. Moreover, sincethe expansion valves 65 and 66 are closed, the separated liquidrefrigerant pools in this gas-liquid separator 4. In the first controlmethod of the present embodiment, the refrigerant recovering operationis performed as described above.

As described above, in the refrigerating device 30 of the presentembodiment, the refrigerant recovered from the heat sink 58 is stored inthe gas-liquid separator 4. Therefore, the fan 2F does not have to beespecially turned on during the refrigerant recovering operation, and itis possible to suppress power consumption and operation noise of therefrigerating device 30.

Furthermore, since carbon dioxide is used as the refrigerant in therefrigerating device 30 of the present embodiment, thehigh-pressure-side circuit of the refrigeration cycle including theradiator 2 is sometimes operated with the supercritical pressure. Inthis case, since the radiator 2 has a supercritical state therein, therecovered refrigerant cannot condense in the radiator 2 as in theconventional example.

However, in the refrigerating device 30 of the present embodiment, therefrigerant recovered from the heat sink 58 is stored in the gas-liquidseparator 4 as described above. Therefore, even in a case where thesupercritical pressure is brought in the high-pressure-side circuit, therefrigerant recovering operation can be performed.

It is to be noted that in a case where the high-pressure-side circuitdoes not have the supercritical pressure, the control device 26 turns onthe fan 2F disposed close to the radiator 2. Accordingly, therefrigerant recovered and thereafter discharged by the compressor 1 isallowed to condense in the radiator 2. This is applicable depending onuse mode or installation place.

Furthermore, in the present embodiment, even in a case where thehigh-pressure-side circuit has a supercritical pressure, the fan 2F isturned on to thereby further cool the refrigerant, and a refrigerantrecovering speed can be increased. In this case, power consumption orthe like increases. However, this is applicable depending on the usemode or the installation place.

Moreover, in a case where it is judged by a value detected by an outsideair sensor (not shown) or the like that the high-pressure-side circuitof the refrigerating device 30 is operated with the supercriticalpressure, the control device 26 executes a control so as to store therefrigerant recovered by the refrigerant recovering operation in thegas-liquid separator 4. On the other hand, in a case where it is judgedthat the high-pressure-side circuit is not operated with thesupercritical pressure, the control device 26 may store the refrigerantrecovered by the refrigerant recovering operation in the gas-liquidseparator 4 and/or the radiator 2.

After such refrigerant recovering operation, the control device 26closes the expansion valves 65 and 66, and turns off the compressor 1and the fans 57F, 58F. Accordingly, the operation in the refrigeratingdevice 30 is stopped. Thereafter, in the refrigerating device 30 of thepresent embodiment, the control device 26 opens the expansion valve 65,closes the expansion valve 66, turns on the fan 57F, and turns off thefan 58F. Accordingly, the freezing operation is performed as describedabove. Thereafter, the freezing operation is executed again. In thefirst control method of the present embodiment, the operations aresuccessively executed as described above.

Second Control Method

Next, there will be described a second control method in the presentembodiment with reference to FIG. 5. In this second control method, arefrigerant recovering operation is executed immediately before arefrigerating operation starts.

First, in an operation stop state in which the expansion valves 65 and66 are closed, and the compressor 1 and the fans 57F, 58F are turnedoff, the refrigerant recovering operation is performed to recover therefrigerant stored in the heat sink 58 by the freezing operation beforeperforming the refrigerating operation.

In this case, the control device 26 opens the expansion valve 65, closesthe expansion valve 66, and turns on the fans 57F, 58F. Moreover, thecontrol device 26 operates the compressor 1 at a frequency higher thanthat during usual operation. It is to be noted that a part shown by aone-dot chain line in the timing chart of the compressor 1 in FIG. 5 isa timing at which the compressor 1 is operated at the high frequency.

Consequently, during the refrigerant recovering operation in the presentsecond control method, the pressure in the heat sink 57 becomes lowerthan that in the heat sink 58. Furthermore, the fan 58F is turned on topromote the evaporation of the refrigerant stored in the heat sink 58,so that the compressor 1 sucks and recovers the stored refrigerant. Therecovered refrigerant pools in the gas-liquid separator 4 or the like asdescribed above in the first control method. In the second controlmethod of the present embodiment, the refrigerant recovering operationis performed as described above, and thereafter the refrigeratingoperation and the freezing operation are successively executed.

Next, there will be described an example in which the refrigeratingdevice 30 of the present embodiment is applied to a refrigerator withreference to FIG. 6.

FIG. 6 shows a schematic constitution diagram of the refrigeratorincluding the refrigerating device 30 of the present embodiment. Thisrefrigerator 40 includes an upper-stage refrigerating chamber 41, and alower-stage freezing chamber 42. Moreover, in-chamber partition walls61, 62 are disposed in inner parts of the chambers 41, 42, respectively.The above-described heat sinks 57, 58, and fans 63, 64 are disposed inan air path 44 defined by the in-chamber partition walls 61, 62. Atemperature sensor 42T is disposed in the freezing chamber 42, and atemperature sensor 41T is disposed in the refrigerating chamber 41.

In the present constitution, when a thermostat turns on or off duringthe refrigerating operation and the freezing operation, the first heatabsorbing means 10 and the second heat absorbing means 11 are switchedas described above. The refrigerant is passed through one of the heatsinks 57, 58, and the corresponding fans 63, 64 are driven. In a casewhere the refrigerant flows in the heat sink 57, cold air is supplied tothe refrigerating chamber 41. In a case where the refrigerant flows intothe heat sink 58, cold air is supplied to the freezing chamber 42.

As described above, since the refrigerator 40 of the present embodimentincludes the refrigerating device 30 constituted as described above, itis possible to obtain a high cooling performance and a high efficiencyoperation even in a case where carbon dioxide is used in therefrigerant. Furthermore, in the refrigerator 40, if the above-describedfirst or second control method is performed by the fans 63, 64 insteadof the fans 57F, 58F, the refrigerant recovering operation can beexecuted.

It is to be noted that in the refrigerating device 30 of the presentembodiment, during the freezing operation, the expansion valve 65 isclosed, and the expansion valve 66 is opened to circulate therefrigerant in the second heat absorbing means 11. During therefrigerating operation, the expansion valve 66 is closed, and theexpansion valve 65 is opened to circulate the refrigerant in the firstheat absorbing means 10. The present invention is not limited to thisembodiment. In, for example, the refrigerator 40, in a case where therefrigerating chamber 41 and the freezing chamber 42 at room temperatureneed to be rapidly cooled during so-called pull-down, in a case wherethe compressor 1 is started to operate from the operation stop state, orhighly loaded, or in a case where the temperature of the refrigeratingchamber 41 or the freezing chamber 42 is not less than a predeterminedtemperature, both the expansion valves 65 and 66 are opened at arequired open degree. Accordingly, the refrigerant is circulated onopposite sides of the first heat absorbing means 10 and the second heatabsorbing means 11, and the chambers 41, 42 can be rapidly cooled,respectively.

Embodiment 2

Next, another embodiment of the present invention will be described withreference to FIG. 7. FIG. 7 shows a refrigerant circuit diagram of arefrigerating device 50 in this case. In the present embodiment,components denoted with the same reference numerals of Embodiment 1 haveidentical or similar functions or effects. The present embodiment isdifferent from Embodiment 1 in that third heat absorbing means 10B isdisposed instead of the first heat absorbing means 10, and fourth heatabsorbing means 11B is disposed instead of the second heat absorbingmeans 11.

The third heat absorbing means 10B includes a refrigerant circulationcontrol valve 93, a capillary tube 12, and a heat sink 57. The fourthheat absorbing means 11B includes a refrigerant circulation controlvalve 94, a capillary tube 13 having a resistance value larger than thatof the capillary tube 12, and a heat sink 58. That is, the third andfourth heat absorbing means 10B, 11B include the refrigerant circulationcontrol valves 94, 95 and the capillary tubes 12, 13 instead of theexpansion valves 65 and 66 in the first and second heat absorbing means10, 11.

In the refrigerating device 50 of the present embodiment, therefrigerant circulation control valves 94, 95 have a function ofrefrigerant channel switching means. A control device 26 closes one ofthe valves to thereby perform the freezing operation in a case where therefrigerant is passed on a capillary tube 13 side, and perform therefrigerating operation in a case where the refrigerant is passed on acapillary tube 12 side.

Moreover, even in the present embodiment, operations can be executed byfirst and second control methods in the same manner as in Example 1. Inthis case, instead of an opening/closing operation of the expansionvalves 65 and 66, the refrigerant circulation control valves 94, 95 areopened and closed.

As described above, since the refrigerating device 50 of the presentembodiment does not include the expansion valves 65 and 66, the presentinvention can be realized at low cost. Needless to say, therefrigerating device 50 of the present embodiment is applicable to arefrigerator in the same manner as in the refrigerating device 30 ofEmbodiment 1.

Embodiment 3

Next, another embodiment of the present invention will be described withreference to FIG. 8. FIG. 8 shows a refrigerant circuit diagram of arefrigerating device 70 in this case. In the present embodiment,components denoted with the same reference numerals of the aboveembodiments have identical or similar functions or effects. The presentembodiment is different from Embodiment 1 in that the refrigeratingdevice includes a three-way valve 91 as refrigerant channel switchingmeans, fifth heat absorbing means 10C instead of the first heatabsorbing means 10, and sixth heat absorbing means 11C instead of thesecond heat absorbing means 11.

The fifth heat absorbing means 10C includes a capillary tube 12 and aheat sink 57. The sixth heat absorbing means 11C includes a capillarytube 13 having a resistance value larger than that of the capillary tube12, and a heat sink 58. That is, the fifth and sixth heat absorbingmeans 10C, 11C include the capillary tubes 12, 13 instead of theexpansion valves 65 and 66 in the first and second heat absorbing means10, 11, and the means include the three-way valve 91 as the refrigerantchannel switching means. It is to be noted that the three-way valve 91is also switchable into a state in which any refrigerant is not passedon a capillary tube 12 or 13 side.

In the refrigerating device 70 of the present embodiment, the controldevice 26 controls the switching of the three-way valve 91 to circulatethe refrigerant in one of the fifth and sixth heat absorbing means 10C,11C. Accordingly, a freezing operation and a refrigerating operation areswitched.

Moreover, even in the present embodiment, the operations can be executedby first and second control methods in the same manner as in Example 1.In this case, instead of an opening/closing operation of the expansionvalves 65 and 66, the circulation of the refrigerant into the heatabsorbing means 10C, 11C may be selected by the three-way valve 91.

As described above, since the refrigerating device 70 of the presentembodiment does not include the expansion valves 65 and 66, the presentinvention can be realized at low cost. Needless to say, therefrigerating device 70 of the present embodiment is applicable to arefrigerator in the same manner as in the refrigerating devices 30, 50of the above embodiments.

The present invention has been described above in detail in accordancewith the embodiments, but the present invention is not limited to them,and can be variously modified. For example, in the above embodiments,the carbon dioxide refrigerant is introduced in the refrigerant circuit,but the present invention is not limited to the embodiments, and thepresent invention is also applicable to a case where another refrigerantsuch as a Freon-based or hydrocarbon-based refrigerant is introduced.The expansion valve 3 may be replaced with a capillary tube ifnecessary.

1. A refrigerating device provided with a refrigeration cycle including:a compressor; a radiator connected to a discharge side of thecompressor; first pressure reducing means connected to an outlet side ofthe radiator; a gas-liquid separator connected to an outlet side of thefirst pressure reducing means; first heat absorbing means through whicha liquid refrigerant from the gas-liquid separator flows and whichincludes second pressure reducing means and a first heat sink; andsecond heat absorbing means disposed in parallel with the first heatabsorbing means and including third pressure reducing means and a secondheat sink, refrigerant pipes of the first and second heat absorbingmeans on the outlet side being combined and connected to a suction sideof the compressor, the second heat absorbing means functioning in atemperature zone lower than that of the first heat absorbing means, afirst cooling operation to operate the first heat absorbing means and asecond cooling operation to operate the second heat absorbing meansbeing switchable to each other, the refrigerating device comprising:control means for performing a refrigerant recovering operation to stopcirculation of the refrigerant into the second heat absorbing means,operate the compressor, recover the refrigerant stored in the secondheat sink, and store the refrigerant in the gas-liquid separator in astate in which circulation of the refrigerant into the first heatabsorbing means is stopped after the second cooling operation iscompleted.
 2. The refrigerating device according to claim 1, furthercomprising: blowing means for sending air to the second heat sink, theblowing means being operated during the refrigerant recoveringoperation.
 3. The refrigerating device according to claim 1 or 2,wherein the compressor has an intermediate pressure section, therefrigerating device further comprising: a refrigerant pipe capable ofintroducing a gas refrigerant separated by the gas-liquid separator intothe intermediate pressure section.
 4. The refrigerating device accordingto any one of claims 1 to 3, wherein a high-pressure side of therefrigeration cycle is operated with a supercritical pressure.
 5. Therefrigerating device according to any one of claims 1 to 4, wherein therefrigerant recovered from the second heat sink is stored in thegas-liquid separator in a case where the high-pressure side of therefrigeration cycle is operated with the supercritical pressure, and therefrigerant recovered from the second heat sink is stored in thegas-liquid separator and/or the radiator in a case where thehigh-pressure side of the refrigeration cycle is not operated with thesupercritical pressure.
 6. The refrigerating device according to claim5, wherein the blowing means for sending air to the radiator is disposedclose to the radiator, and the blowing means is operated at a time whenthe refrigerant recovered from the second heat sink is stored in theradiator.
 7. A refrigerating device provided with a refrigeration cycleincluding: a compressor; a radiator connected to a discharge side of thecompressor; first pressure reducing means connected to an outlet side ofthe radiator; a gas-liquid separator connected to an outlet side of thefirst pressure reducing means; first heat absorbing means through whicha liquid refrigerant from the gas-liquid separator flows and whichincludes second pressure reducing means and a first heat sink; andsecond heat absorbing means disposed in parallel with the first heatabsorbing means and including third pressure reducing means and a secondheat sink, refrigerant pipes of the first and second heat absorbingmeans on the outlet side being combined and connected to a suction sideof the compressor, wherein the second heat absorbing means functions ina temperature zone lower than that of the first heat absorbing means, afirst cooling operation to operate the first heat absorbing means and asecond cooling operation to operate the second heat absorbing means areswitchable to each other, the refrigerating device permittingcirculation of the refrigerant into the first heat absorbing means,stopping circulation of the refrigerant into the second heat absorbingmeans, and operating the compressor at a frequency higher than that ofthe first or second cooling operation before starting the first coolingoperation.
 8. A refrigerating device provided with a refrigeration cycleincluding: a compressor; a radiator connected to a discharge side of thecompressor; first pressure reducing means connected to an outlet side ofthe radiator; a gas-liquid separator connected to an outlet side of thefirst pressure reducing means; first heat absorbing means through whicha liquid refrigerant from the gas-liquid separator flows and whichincludes second pressure reducing means and a first heat sink; andsecond heat absorbing means disposed in parallel with the first heatabsorbing means and including third pressure reducing means and a secondheat sink, refrigerant pipes of the first and second heat absorbingmeans on the outlet side being combined and connected to a suction sideof the compressor, wherein the second heat absorbing means functions ina temperature zone lower than that of the first heat absorbing means, afirst cooling operation to operate the first heat absorbing means and asecond cooling operation to operate the second heat absorbing means areswitchable to each other, the refrigerating device performing arefrigerant recovering operation of permitting circulation of therefrigerant into the first heat absorbing means, stopping circulation ofthe refrigerant into the second heat absorbing means, operating thecompressor at a frequency higher than that of the first or secondcooling operation, recovering the refrigerant stored in the second heatsink, and sending the refrigerant to the gas-liquid separator to storethe refrigerant before starting the first cooling operation.
 9. Therefrigerating device according to claim 7 or 8, further comprising:blowing means for sending air to the second heat sink, the blowing meansbeing operated in a case where the compressor is operated at the highfrequency.
 10. The refrigerating device according to any one of claims 1to 9, wherein carbon dioxide is used as the refrigerant.
 11. Arefrigerator comprising: a refrigerating device according to any one ofclaims 1 to
 10. 12. The refrigerator according to claim 11, furthercomprising: a refrigerating chamber; and a freezing chamber operated ata temperature lower than that of the refrigerating chamber, therefrigerating chamber being cooled by the first heat absorbing means,the freezing chamber being cooled by the second heat absorbing means.